U.S. patent number 6,169,410 [Application Number 09/189,091] was granted by the patent office on 2001-01-02 for wafer probe with built in rf frequency conversion module.
This patent grant is currently assigned to Anritsu Company. Invention is credited to Martin I. Grace, William W. Oldfield.
United States Patent |
6,169,410 |
Grace , et al. |
January 2, 2001 |
Wafer probe with built in RF frequency conversion module
Abstract
A wafer probe with built in components to perform frequency
multiplication, upconversion, downconversion, and mixing typically
performed by an RF module of a vector network analyzer (VNA). The
wafer probe is designed for testing integrated circuits used in
collision avoidance radar systems and operates over the 76-77 GHz
frequency range allocated by the Federal Communications Commission
(FCC) for collision avoidance radars. To minimize costs, the wafer
probe preferably utilizes integrated circuits for frequency
multiplication, upconversion, downconversion, and mixing
manufactured for collision avoidance radar systems.
Inventors: |
Grace; Martin I. (San Jose,
CA), Oldfield; William W. (Redwood City, CA) |
Assignee: |
Anritsu Company (Morgan Hill,
CA)
|
Family
ID: |
22695897 |
Appl.
No.: |
09/189,091 |
Filed: |
November 9, 1998 |
Current U.S.
Class: |
324/754.07;
324/537; 324/762.05 |
Current CPC
Class: |
G01R
1/06772 (20130101) |
Current International
Class: |
G01R
1/067 (20060101); G01R 031/02 (); H01H
031/02 () |
Field of
Search: |
;324/754,537,755 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Metjahic; Safet
Assistant Examiner: Hollington; Jermek M.
Attorney, Agent or Firm: Fliesler, Dubb, Meyer &
Lovejoy, LLP
Claims
What is claimed is:
1. A wafer probe comprising:
a housing;
a wafer probe tip supported by the housing for making electrical
contact with circuits on a wafer;
a first cable having a first end supported by the housing, the
first cable further having a second end coupled to receive an RF
signal from a first signal source;
a first frequency multiplier supported by the housing, the
frequency multiplier having an input coupled to the first end of
the first cable for receiving the RF signal, and having an
output;
a first coupler supported by the housing, the first coupler having
a first, a second and a third terminal, wherein the first coupler
includes a through path connecting the first and second terminals,
wherein the first terminal is coupled to the output of the first
frequency multiplier, the first coupler further having a coupling
path coupling the first terminal to the third terminal;
a second coupler supported by the housing, the second coupler
having a first, a second and a third terminal, the second coupler
having a through path connecting the first and second terminals of
the second coupler, wherein the first terminal of the second
coupler is coupled to the wafer probe tip, and the second terminal
of the second coupler is coupled to the second terminal of the
first coupler, the second coupler further having a coupling path
coupling the first terminal of the second coupler to the third
terminal of the second coupler;
a second cable having a first end supported by the housing, the
second cable further having a second end coupled to receive a local
oscillator (L0) signal from a second signal source;
a power divider having an input coupled to the first end of the
second cable to receive the LO signal, and having a first output
and a second output;
a second frequency multiplier supported by the housing, the second
frequency multiplier having an input coupled to the first output of
the power divider and having an output;
a third frequency multiplier supported by the housing, the third
frequency multiplier having an input coupled to the second output
of the power divider and having an output
a first mixer supported by the housing, the first mixer having a
first input, a second input and an output, wherein the first input
is coupled to the third terminal of the first coupler, the second
input is coupled to the output of the second frequency multiplier
and the output provides a reference IF signal; and
a second mixer supported by the housing, the second mixer having a
first input, a second input and an output, wherein the first input
of the second mixer is coupled to the third terminal of the second
coupler, wherein the second input of the second mixer coupled to
the output of the third frequency multiplier and wherein the output
of the second mixer provides a test IF signal.
2. The wafer probe of claim 1 further comprising:
a fourth frequency multiplier coupling the output of the first
frequency multiplier to the first terminal of the first
coupler.
3. The wafer probe of claim 1 further comprising:
a fourth frequency multiplier coupling the output of the second
frequency multiplier to the second input of the first mixer;
and
a fifth frequency multiplier coupling the output of the third
frequency multiplier to the second input of the second mixer.
4. The wafer probe of claim 3 further comprising:
a sixth frequency multiplier coupling the output of the first
frequency multiplier to the first terminal of the first coupler.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to components for a vector network
analyzer (VNA) and wafer probe which may be used to test integrated
circuits manufactured for an automobile collision avoidance
radar.
2. Description of the Related Art
Recently, automobile manufacturers, have provided collision
avoidance radar systems in a limited number of vehicle models.
Collision avoidance radar systems have also recently been made
available for purchase by consumers for installation on trucks or
automobiles. An example of such a system is the Eaton.RTM.
VORAD.RTM. Collision Warning System available from Eaton VORAD
Technologies, L.L.C., of San Diego, Calif.
Collision avoidance radar systems currently available operate by
transmitting and receiving signals using an antenna located in the
front grill area of a vehicle. The collision avoidance radar
determines from a delay before a return signal is received, or from
a frequency shift in a signal received, a distance an object
causing the return signal is located from the vehicle and how fast
the object is traveling relative to the vehicle.
Collision avoidance radar systems typically operate within a narrow
frequency band. In the United States, the Federal Communications
Commission (FCC) has allocated the frequency range of 76-77 GHz for
collision avoidance radars.
A VNA is typically used with an attached wafer probe to test
microwave integrated circuit components manufactured for a
collision avoidance radar. A traditional VNA is an expensive system
designed to operate over a wide range of frequencies. FIG. 1 shows
a block diagram of typical components included in a VNA. As shown,
the VNA includes signal sources 100-101, a test set 102, test
modules 104-105, and a VNA controller 108.
A typical signal source which may be used for the LO signal source
100 and RF signal source 102 for a VNA is the Anritsu model 68037B,
manufactured by Anritsu Company of Morgan Hill Calif. The 68037B
signal source operates over a 2-20 GHz frequency range and provides
power up to +17 dBm. The frequencies for the signal sources 100-101
are controlled by VNA controller 108 through signals over a general
purpose interface bus (GPIB). An example of a VNA controller is the
37100A manufactured by Anritsu Company.
The LO signal from signal source 100 and the RF signal from signal
source 101 are provided to a test set 102, such as the 3735A test
set manufactured by Anritsu Company. Components included in the
test set are shown in FIG. 2. The test includes a transfer switch
200 which selectively provides the RF drive signal from the RF
signal source 101 to either the RF port 1 which connects to RF
module 104, or to the RF port 2 which connects to the RF module
105. The transfer switch 200 is controlled by a signal received
from the VNA controller 108. A power divider 202 provides the LO
signal from the LO signal source 100 to the LO ports of the RF
modules 104 and 105. The test set 102 further includes a power
supply 204 and a printed circuit board (PCB) assembly 206. The
power supply 204 converts a standard 115V AC signal to 12V and 15V
DC signals. The PCB assembly 206, then provides further voltage
regulation and distributes 12V and 15V signals to the RF modules
104 and 105 and forwards the transfer switch control signal to the
transfer switch 200. The test set 102 further forwards the test IF
and reference IF signals from the RF modules 104 and 105 to the VNA
controller 108 as S-Parameter signals a1, a2, b1, and b2.
Components for RF modules 104 and 105 are shown in FIG. 3. An
example of the RF module shown is the Anritsu 3741A-X millimeter
wave module. The RF module of FIG. 3 contains multipliers 300 and
302 to enable a maximum 20 GHz output from the RF signal source 101
to be multiplied up to 80 GHz to provide coverage of the 76-77 GHz
bandwidth for collision avoidance radar systems. Amplifier 304
serves to boost the input signal to the multiplier, while the
output of multiplier 300 is amplified by amplifier 306. Amplifiers
304 and 306 receive power from the +12V output of the test set 102.
Although the multipliers 300 and 302 are shown as times two
(.times.2) devices, the multiplication factor is altered in test
sets designed to cover frequency bands other than the 76-77 GHz
bandwidth for collision avoidance radars.
An RF test signal is provided from multiplier 302 through dual
directional coupler 308 to a test port as a test signal. The dual
directional coupler 308 serves to provide both the test signal and
a reference signal for analysis. The reference signal is provided
from a first directional coupler in the dual coupler 308 which
couples an incident signal provided from the RF signal source 101
through multipliers 300 and 302 and amplifiers 304 and 306 to a
harmonic mixer 310. The test signal is received from a second
coupler in dual coupler 308 which couples a transmitted or
reflected signal from the test port to a harmonic mixer 312. The
test signal results from reflections from a test device connected
to the test port which will occur if an impedance mismatch exists.
When a mismatch occurs, some of the test signal incident at the
port will travel into the test device, and some will be reflected
back to the test port. The transfer switch 200 of the test set 102
may provide the test signal through another RF module to measure
parameters of a two port test device. With a test signal provided
from a second RF module in a two port device, the portion of the
signal that travels through the test device goes to the test port
of the first RF module for measurement.
The harmonic mixers 310 and 312 mix the RF signals from the dual
directional coupler 308 with the LO signal provided to the mixers
through amplifier 313 and power divider 314 to downconvert the RF
test and reference signals to 270 MHZ intermediate frequency (IF)
signals TEST IF and REF IF. The amplifier 313 is a limiting
amplifier used to keep the LO power at a fixed level into the
harmonic mixers. The amplifier 320 provides the TEST IF signal from
mixer 312, while the amplifier 322 provides the REF IF signal from
the mixer 310. Amplifiers 313, 320, and 322 receive power from the
+15V output of the test set 102. The TEST IF and REF IF signals are
provided from the RF modules 104-105 to the VNA controller 108 via
the test set 102. The TEST IF signal carries embedded magnitude and
phase information relative to the REF IF signal.
An example of the VNA controller is the Anritsu 37100A. A typical
VNA controller includes synchronous detectors, a digital signal
processor or microprocessor, and a display. The synchronous
detectors convert the TEST IF and REF IF signals to digital signal
data. The VNA processor controlled by embedded firmware coupled
with system software, manipulates this digital data. Resultant
S-Parameter data characterizing the test device is then presented
on the display, and can also be output to a printer or plotter, or
routed to the rear panel external GPIB interface.
A wafer probe is an accessory which may be attached to test ports
of a VNA enabling the VNA to be used to measure components for a
wafer. Measurements on a wafer are performed before wafer circuits
are separated or diced.
SUMMARY OF THE INVENTION
The present invention was developed with recognition that with a
potential increase in demand for collision avoidance radar systems,
it will be desirable to have a test system operating over a narrow
bandwidth of the collision avoidance radar system to reduce test
equipment cost.
The present invention was further developed with recognition that
millimeter microwave integrated circuits (MMICs) used in collision
avoidance radar systems are similar to components required in the
RF module of a VNA, and the MMICs will operate over the narrow
collision avoidance radar frequency range of 76-77 GHz. The present
invention was further developed with recognition that the MMICs for
collision avoidance radar systems multiply the signal source
frequency so that a low cost low frequency signal source can be
used to create a signal in the 76-77 GHZ range. The most complex
and expensive parts of the VNA are in its signal sources and RF
module, particularly for a VNA operating over a wide range of
millimeter microwave frequencies. With increasing numbers of
collision avoidance radar systems, the cost of MMICs used in the
radar has been reduced, and is expected to be reduced further with
increasing demand over time.
The present invention is a wafer probe with built in components to
perform frequency multiplication, upconversion, downconversion and
mixing typically performed by a RF module of a VNA. The wafer probe
is designed for testing integrated circuits used in collision
avoidance radar systems and operates over a slightly wider
bandwidth than the 76-77 GHz frequency range allocated by the FCC
for collision avoidance radars. By operating only near the 76-77
GHz collision avoidance radar frequency, the RF and LO signal
sources can operate over a narrower frequency range than typical
signal sources used with a VNA, and will be less expensive. Further
minimizing costs, the wafer probe of the present invention
preferably uses integrated circuits for frequency multiplication,
upconversion, downconversion, and mixing manufactured for collision
avoidance radar systems. Such integrated circuits will operate over
the desired 76-77 GHz frequency range and will experience a
reduction in cost as increased numbers of the collision avoidance
radar systems are manufactured.
BRIEF DESCRIPTION OF THE DRAWINGS
Further details of the present invention are explained with the
help of the attached drawings in
FIG. 1 shows typical components included in a VNA;
FIG. 2 shows components for the test set of FIG. 1;
FIG. 3 shows components for the RF modules of FIG. 1;
FIG. 4 shows components included in a wafer probe of the present
invention; and
FIG. 5 shows a wafer probe with a layout for built in components of
the RF module of FIG. 4.
DETAILED DESCRIPTION
FIG. 4 shows components built into one or more wafer probes of the
present invention along with connections to components of a signal
generator and test set provided separate from the wafer probes. The
wafer probes of the present invention can each include built in
components for one of the RF modules 401-402. The need for RF
modules provided separate from wafer probes used with a VNA, such
as RF modules 104 and 105 illustrated with respect to FIG. 1 is,
thus, eliminated.
The RF modules 401-402 receive an RF signal from a separate RF
signal source 410, similar to the RF signal source 101 of FIG. 1.
The RF signal source 410 is designed to operate over a
19.125.+-.0.5 GHz range which will be multiplied up to a 74.5-78.5
GHz range in the RF modules 401-402 to enable testing throughout
the 76-77 GHz collision avoidance radar bandwidth. With only a
19.125.+-.0.5 GHz output signal required, a lower cost device can
be used for the RF signal source 410 than a broadband device
typically providing a 2-20 GHz, such as the Anritsu 68037B signal
source as discussed previously. The output of the RF signal source
410 is provided to the RF modules 401-402 through a transfer switch
414 of a test set, similar to transfer switch 202 of FIG. 2.
The RF modules 401-402 further receive a LO signal from a separate
LO signal source 416, similar to the LO signal source 100 of FIG.
1. The LO signal source 416 is designed to operate over a
19.125.+-.0.5 GHz range which will be multiplied up to a 74.5-78.5
GHz range in the RF modules 401-402 for mixing with the RF signals
with the signal frequency adjusted by a VNA controller to create an
IF signal, such as the 270 MHz IF signal described earlier. With
only a 19.125.+-.0.5 GHz output signal required, a lower cost
device can be used for the LO signal source 416 than a broadband
2-20 GHz device typically used. The output of the LO signal source
416 is provided to the RF modules 401-402 through a power divider
418 of a test set, similar to power divider 202 of FIG. 2.
The RF modules 401-402 include the same components, so a
description of the components of the RF modules 401-402 will be
made only with respect to RF module 401. In RF module 401, an RF
signal from the transfer switch is received by a circuit 420
labeled OSC40. The OSC40 circuit 420 includes a frequency
multiplier 422, and buffers 421 and 423 integrated onto a single
circuit. The frequency multiplier 422 multiplies the 19.125.+-.0.5
GHz signal by two to provide an output in the range of 38.25.+-.1
GHz. An example of the OSC40 circuit which is commercially
available is the CHV1040 Multifunction:K-band Oscillator and Q-band
Multiplier manufactured by united monolithic semiconductors
S.A.S.
The output signal from the OSC circuit 420 is provided to a circuit
425 labeled MFC3776. The MFC3776 circuit 425 includes a frequency
multiplier 427, and buffers 426 and 428 integrated onto a single
circuit. The frequency multiplier 427 multiplies the 38.25.+-.1 GHz
signal from the OSC40 circuit 420 by two to provide an output in
the range of 76.5.+-.2 GHz. An example of the MFC3776 circuit which
is commercially available is the CHU2077 W-band Multifunction
MultiplieriMPA manufactured by united monolithic semiconductors
S.A.S.
The output of the MFC3776 circuit 425 is provided through couplers
430 and 432 to the test port which is connected to a wafer probe
contact. The couplers 430 and 432 are formed on a substrate as a
microstrip circuit using conventional chemical vapor deposition and
etching procedures. The coupler 430 serves to couple the output
signal from the MFC3776 circuit 425 as an incident reference signal
to a mixer circuit 434. The coupler 432 serves to couple a signal
received at the test port as a test signal to the mixer circuit
436.
To provide a LO signal to the mixer circuits 434 and 436, a power
divider 437 provides the LO signal from power divider 418 to OSC40
circuits 438 and 439. The power divider 437 is formed on a
substrate as a microstrip circuit using conventional chemical vapor
deposition and etching techniques.
The OSC40 circuits 438-439 each include the same components as the
OSC40 circuit 420 and serve to multiply the 19.25.+-.0.5 LO signal
by two to provide a 38.25.+-.1 GHz output. The output of the OSC40
circuits 438 and 439 are provided to the inputs of respective
MCF3776 circuits 440 and 441. The MCF3776 circuits 440-441 each
include the same components as the MCF3776 circuit 425 and serve to
multiply the 38.25.+-.1 GHz signal by two to provide a 76.5.+-.2
GHz output to the LO inputs of respective mixers 434 and 436.
The mixer 434 serves to mix the reference RF signal with the LO
signal from the circuit 440 to provide a reference IF signal (REF
IF). The REF IF signal can then be provided from a wafer probe to a
test set, such as 102 of FIG. 1, and then from the test set to a
VNA controller, such as 108 of FIG. 1. The mixer 436 serves to mix
the test RF signal with the LO signal from the circuit 441 to
provide a test IF signal (TEST IF). The TEST IF signal can also be
provided from the wafer probe through a test set to a VNA
controller. An example of an integrated circuit for either of the
mixers 434 and 436 is the W-band Double Mixer manufactured by
united monolithic semiconductors S.A.S.
As in FIG. 1, the VNA controller such as the Anritsu 3735A can be
used to provide a signal over a GPIB to control the frequency of
the RF signal source 410 and the LO signal source 416. The LO
signal source frequency is offset from the RF signal source
frequency to provide a test signal in the range of 270 MHz.
Although not shown, the VNA controller can also provide signals
over a GPIB to a PCB assembly of a test set, such as the PCB
assembly 206 of FIG. 2, to control a voltage level provided to the
amplifying buffers of the OSC40 and MCF3776 circuits to control
amplifier gain.
FIG. 5 shows a layout of components of the RF module 401 of FIG. 4
built into a wafer probe. The wafer probe includes a housing 501.
The housing supports a probe tip 502 which is contacted to circuits
on a wafer to enable testing the wafer. The RF module 401 is placed
on a substrate which is supported by the housing 501. With
integrated circuit components used which are manufactured by united
monolithic semiconductors S.A.S., as described above, the RF module
401 can occupy an area as small as of 0.617 in by 0.690 in.,
enabling the RF module 401 to be included on the wafer probe
instead of on a device separate from the wafer probe. The test port
of the RF module 401 as provided from coupler 432 provides a signal
to the probe tip 502. A cable 504 connects the OSC40 circuit 420 to
a test set to receive the output of a RF signal source. A cable 506
connects the power divider 437 to a test set to receive the output
of a LO signal source. Additional cables or wiring (not shown) will
be further connected to the RF module 401 to provide +12V and +15V
DC signals to amplifiers.
Although the present invention has been described above with
particularity, this was merely to teach one of ordinary skill in
the art how to make and use the invention. Many other modifications
will fall within the scope of the invention, as that scope is
defined by the claims provided below. For example, with further
development of collision avoidance radar systems, new components
may be available to perform upconverting, downconverting, and
mixing performed by the components shown in FIG. 4 making up RF
module 401. For instance, components from the OSC40 and MFC3776
circuits may be combined onto a single chip. Further, the mixers
434 and 436 may be combined with frequency multipliers from the
OSC40 and MFC3776 chips onto a single chip. Use of such chips, or
only a portion of such chips, is believed within the scope of the
present invention.
* * * * *